1. Field of Invention
The present invention relates to phosphorus-containing compounds. More particularly, the present invention relates' to a bisphenol epoxy resins containing phosphorus and the methods for synthesizing the same.
2. Description of Related Art
Traditional printed circuit boards were usually formed by curing an epoxy resin containing a flame retardant containing halogen and antimony trioxide. However, corrosive gas and carcinogens, such as dioxin and benzofuran, will be produced when the epoxy resin above is burned.
Recently, it is found that organic phosphorous compounds added into polymer can make the polymer more flame-retardant. Furthermore, less toxic gases and smoke will be produced when the organic phosphorous compounds are burned. Therefore, an organic phosphorus containing bisphenol monomer, HPP, is introduced into an epoxy monomer to form an epoxy resin, and the chemical structure of the HPP is shown below:

Since an alkaline solution is needed in several steps of the manufacturing process of printed circuit boards, the epoxy resin for making the printed circuit boards should be alkali resistance. However, the central C—H connected to the P atom in the chemical structure above is active hydrogen. Thereby preventing the epoxy resin containing the phosphorus bisphenol moiety from being used to make printed circuit boards.